1. Field of the Invention
The present invention relates generally to the molding of vehicle supporting elements formed of rubber and more particularly, to a system for molding rubber tractor tracks in an endless configuration.
2. Description of the Prior Art
Molded rubber tractor tracks are in many cases being substituted for conventional metal tractor tracks. Rubber tractor tracks offer better maneuverability, better ride quality in rough fields, better flotation in wet fields, improved side hill stability, excellent traction, low maintenance and versatility compared to steel tractor tracks. Additionally, rubber tracks are replacing conventional rubber tires on tractor and other agricultural vehicles such as combines, trenchers, snow removers, spreaders, sprayers, wagons and carts, since rubber tracks are more friendly to agricultural fields, offer better flotation and less compaction than rubber tires, resulting in better crop yield. The use of rubber tractor tracks permits farmers to get out into the fields earlier in the planting season and plant more crops as compared to rubber tire-equipped agricultural vehicles.
Rubber tractor tracks are defined by an endless rubber belt reinforced with continuous flexible steel cables bonded into the rubber. With present commercial methods, a complete rubber tractor track is molded flat in quarter sections which are sequentially then bonded together during the curing process. In practice, the joint between the bonded-together sections tend to break in use. Additionally, the joint between the bonded-together ends is of a different cross-sectional dimension than the cross-sectional dimension of the major portion of the track length. Accordingly, during movement of the track-supported vehicle, the vehicle is subject to severe vibrations. Such vibrations are not only harmful to the vehicle, but also to pavement over which the vehicle is moved. Additionally, such vibration is annoying to the vehicle operator.
Another method involves building a complete track using a drum. Uncured or cured lugs are first manually clamped within pockets formed in the drum. Next, uncured rubber, calendered cord and wire cable are wrapped around the outside of the drum. Preformed uncured treads are then stitched onto the uncured rubber. The drum is then disposed within an autoclave to cure the rubber and the parts attached thereto. The drum is then collapsed to remove the completed track. Since only low pressure can be applied the cured rubber is of a low density with resulting low strength. Also, the track lugs and treads are not generally integrally bonded to the rubber and are displaced during use.